The Company invoices its customers in accordance with billing schedules established in each contract. The Company’s rights to consideration from customers are presented separately in the Company’s Consolidated Balance Sheets depending on whether those rights are conditional or unconditional.

The Company presents unconditional rights to consideration from customers within “Accounts receivable, net” in its Consolidated Balance Sheets. All of the Company’s contracts are generally non-cancellable and/or non-refundable, and therefore an unconditional right generally exists when the customer is billed or amounts are billable per the contract.

	March 31,			December 31,
	2021			2020
Billed and billable	$	152,686		$	200,221
Less: allowance for credit losses		(2,060	)		(2,760	)
Accounts receivable, net	$	150,626		$	197,461

Changes in the allowance for credit losses were not material for the three months ended March 31, 2021. In estimating its allowance for credit losses as of March 31, 2021, the Company considered the impact from the pandemic caused by a novel strain of coronavirus (“COVID-19”) and established additional risk pools and reserves relating to customers in certain geographic areas and industries, in addition to separately assessing the reserves for certain customers that have been granted extended payment terms.

Rights to consideration that are subject to a condition other than the passage of time are considered contract assets and presented within “Prepaid expenses and other current assets” in the Consolidated Balance Sheets since the rights to consideration are expected to become unconditional and transfer to accounts receivable within one year. Contract assets generally consist of accrued sales and usage-based royalty revenue. In these arrangements, consideration is not billed or billable until the royalty reporting is received, generally in the subsequent quarter, at which time the contract asset transfers to accounts receivable and a true-up adjustment is recorded to revenue. These true-up adjustments are generally not material. During the three months ended March 31, 2021 and 2020, there were no significant impairments to the Company’s contract assets, nor were there any significant changes in the timing of the Company’s contract assets being reclassified to accounts receivable. Contract assets included in “Prepaid expenses and other current assets” in the Consolidated Balance Sheets consisted of $1.3 million and $1.1 million in accrued sales and usage-based royalty revenue as of March 31, 2021 and December 31, 2020, respectively.

Contract liabilities are amounts received or due from customers in advance of the Company transferring the software or services to the customer. In the case of multi-year service contracts arrangements, the Company generally does not invoice more than one year in advance of services and does not record deferred revenue for amounts that have not been invoiced and that require an additional contract. Revenue is subsequently recognized in the period(s) in which control of the software or services is transferred to the customer. The Company’s contract liabilities are presented as either current or non-current “Deferred revenue and advance payments” in the Consolidated Balance Sheets, depending on whether the software or services are expected to be transferred to the customer within the next year.

The Company’s “Accounts receivable, net” and “Deferred revenue and advance payments” balances in the Consolidated Balance Sheets include unpaid amounts related to contracts under which the Company has an enforceable right to invoice the customer for non-cancellable and/or non-refundable software and services. Changes in accounts receivable and changes in deferred revenue and advance payments are presented net of these unpaid amounts in “Operating activities” in the Consolidated Statements of Cash Flows.

Deferred revenue and advance payments (in thousands) from customers consisted of the following, as of:

	March 31,		December 31,
	2021		2020
Current:
Deferred product licenses revenue	$	195	$	1,495
Deferred subscription services revenue		25,689		26,258
Deferred product support revenue		167,282		156,216
Deferred other services revenue		5,814		7,281
Total current deferred revenue and advance payments	$	198,980	$	191,250

Non-current:
Deferred product licenses revenue	$	67	$	139
Deferred subscription services revenue		8,317		8,758
Deferred product support revenue		5,401		5,055
Deferred other services revenue		732		710
Total non-current deferred revenue and advance payments	$	14,517	$	14,662

During the three months ended March 31, 2021, the Company recognized revenues of $70.3 million from amounts included in the total deferred revenue and advance payments balances at the beginning of 2021. During the three months ended March 31, 2020, the Company recognized revenues of $69.2 million from amounts included in the total deferred revenue and advance payments balances at the beginning of 2020. For the three months ended March 31, 2021 and 2020, there were no significant changes in the timing of revenue recognition on the Company’s deferred balances.

As of March 31, 2021, the Company had an aggregate transaction price of $213.5 million allocated to remaining performance obligations related to product support, subscription services, other services, and, in limited cases, product licenses contracts. The Company expects to recognize $199.0 million within the next 12 months and $14.5 million thereafter.