One level assessment credit is needed for each Skill Point you wish to earn. For example, to be evaluated on both Level 1 and Level 2 of Table Saw::Ripping, you would use two level assessment credits. Credits never expire. Tool Stamps/Skill Points you earn using credits never expire, they are Lifetime Achievements.
For instant purchase using PayPal or a credit/debit card, select Instant Assessment Credits on this page.