Please ensure that your oven is cleaned thoroughly every 3 months at least, or whenever food spills onto the liner of the oven, this will ensure a long lifespan of your oven. Please note there should never be anything left on the inside bottom of ovens (including foil trays) as these can cause the heat from the bottom element not to disperse properly and can cause cracking and imperfections in the liner of the oven.
Please follow the cleaning and maintenance instructions from the manual of your specific oven.